In an X-ray diagnostic system, an X-ray tube is provided on the ceiling of a room via a supporting member.
FIG. 19 shows an X-ray tube which is provided on the ceiling of a room via a supporting member. As shown in FIG. 19, the supporting member has a base section 31 and a pillar section 32. The base section 31 is installed on the ceiling C via a rail L. The pillar section 32 has an upper pillar 321, a middle pillar 322 and a bottom pillar 323, which are fitted to each other. The upper pillar 321 is mounted on the base section 31. The X-ray tube 11 is provided on the bottom pillar 323 (the lower end portion of a supporting member 30). The height of the X-ray tube 11 is adjusted by extending and contracting the pillar section 32.
Regarding radiography, there is supine full-length radiography in which a subject P is placed on a bed B, in addition to standing full length radiography of the lower extremities in which the subject P is in the standing position. For example, in supine full-length radiography, the X-ray irradiation field has to be widened by making the position of the X-ray tube as high as possible so that images of the extensive part of the subject P lying on the bed can be photographed. In addition, in standing full length radiography of the lower extremities, the position of the X-ray tube has to be as low as possible to capture the images of the heel of the subject P who is standing. In other words, it is necessary to move the X-ray tube 11 over a wide range, from the higher position to the lower position, depending on each mode of photography (supine full-length radiography or standing full length radiography of the lower extremities).
However, if the ceiling in the room is low, the position of the X-ray tube 11 provided on the ceiling via the supporting member becomes low over the entire moving range. In contrast, if the ceiling in the room is high, the position of the X-ray tube 11 provided on the ceiling via the supporting member becomes high over the entire moving range.
The need for moving the X-ray tube 11 over a wide range is now described with reference to FIG. 19 and FIG. 20.
FIG. 19 shows the state of supine full-length radiography. In supine full-length radiography, the SID (source-image distance) should be large since the X-ray irradiation field has to be wide. For this purpose, the position of the X-ray tube 11 needs to be high.
There is a case that that it is not possible to make the position of the X-ray tube 11 sufficiently high by only moving the X-ray tube 11 because the ceiling in the room is low and therefore the position of the X-ray tube 11 is low over the entire moving range. In this case, a large SID (e.g., 2 [m]) should be secured. Thus, for CR (Computed Radiography) and film, without using the bed B, an IP (Imaging Plate) and a cassette are placed on the floor, and the subject P lies on top of them, which is stressful for the subject P.
FIG. 20 shows the status of standing full length radiography of the lower extremities. As shown in FIG. 20, in standing full length radiography of the lower extremities, it is necessary to lower the position of the X-ray tube 11 in order to photograph down to the heel.
There is a case that it is not possible to make the position of the X-ray tube 11 sufficiently low by only moving the X-ray tube 11 because the ceiling in the room is high and therefore the position of the X-ray tube 11 is high over the entire moving range. In this case, the subject P can stand on the platform for photography (a step) S in order to capture images of the heel of the subject; however, it is likely that the subject P undergoing standing full length radiography of the lower extremities may have a disease in the foot; therefore, having the platform for photography as low as possible is less stressful for the subject and safer.
In order to move the X-ray tube 11 over a wide range, from a higher position to a lower position, the supporting member 30 is extended and contracted with a large stroke. Herein, the general stroke for the supporting member 30 is about 1.5 to 1.8 [m].
In order to further enlarge the stroke for the supporting member 30, for example, in the event that the supporting member 30 consists of three members, the upper pillar 321, middle pillar 322 and bottom pillar 323, each of the pillars 321 to 323 should be elongated.
However, when this supporting member 30 is provided on the ceiling and each of the pillars 321 to 323 is contracted, each of the pillars 321 to 323 is long, resulting in the lower end portion of the supporting member becoming low and the position of the X-ray tube 11 provided at the lower end portion of the supporting member 30 also becoming low. Therefore, there was a problem in that it was not possible to raise the position of the X-ray tube 11 sufficiently high, and supine full-length radiography, which requires wider X-ray irradiation field, could not be performed (see FIG. 21).
Next, in order to further enlarge the stroke of the supporting member 30, for example, the supporting member 30 should have multiple pillars, with each pillar able to be shortened. However, there was a problem; since the diameter of the upper pillar became larger, it was also heavier and the multiple pillars meant a complicated structure, causing high costs and a decline in the quality of appearance (see FIG. 22).
In addition, there is a technology in which an adaptor A is added between the ceiling C and the base section 31 to adjust the position of the X-ray tube 11 to fit to the height of the ceiling C (see FIG. 23).
Furthermore, a technology exists in which the X-ray tube 11 is installed in a position at a different height relative to the supporting member 30 when installing the X-ray diagnostic system on the ceiling (e.g. patent document No. 1).